The present invention relates to a method and apparatus for processing an image signal, and more particularly, to a method and apparatus for removing color noise of an image signal in which a distortion of YCbCr color space caused by noise is corrected using correlations between color channels in the YCbCr color space of low and high frequency components of an image signal while maintaining the high frequency component of the image signal.
A conversion of RGB signals, which are continuous signals having different wavelengths, into digital signals causes aliasing in each channel due to sampling if not performed at an optimal sampling frequency. This also causes color noise due to a distortion of correlations between RGB image values.
Conventionally, a smooth variation of R-G and B-G values is used to remove noise. However, the smooth variation of R-G and B-G values is not necessarily maintained in high frequency components of image signals with regard to color noise that occurs due to sampling of image signals at an inappropriate sampling frequency. Furthermore, since an intermediate value of R-G and B-G values is used as a reference value without color noise, edge components that are important in image quality vary when the smooth variation of R-G and B-G values is used to remove color noise, thus resulting in a failure to obtain desired images.